Analytical modelling, design optimisation and numerical simulation of a variable width cantilever beam MEMS switch

Abstract

ABSTRACT Pull-in potential of electrostatic actuation ohmic cantilever beam type RF MEMS switch is lowered by reducing stiffness constant of its cantilever beam. However, this design objective is highly interlinked to major criteria like its mechanical, RF performance parameters, materials used and fabrication constraints. The purpose of this study is to address the design methodology of such interdisciplinary complex phenomenon to obtain global optimum solution. A variable width cantilever beam design is proposed to lower its pull-in potential. The design optimisation methodology adopted in this study uses analytical model of stiffness constant, major interlinked criteria based on cantilever beam profile and geometric dimensions of the switch. This methodology is further identified as a multivariable constraint optimisation problem to be solved using evolutionary optimisation algorithm for various geometric dimensions of the switch. 3-D modelling, simulation of the optimised device for pull-in potential, mechanical and RF performance parameters is carried out using CAD tools. The results obtained from simulation and analytical models are in agreement. The proposed optimised design opens a new avenue in RF MEMS switch design as it satisfies additional essential performance parameters compared to the results of previous published designs concluding significance of design optimisation methodology adopted in this work.